Heat transfer performance comparison of printed circuit heat exchangers with straight, zigzag and serpentine flow channels for waste heat recovery

2021 ◽  
Author(s):  
Jun‐Yu Xie ◽  
Chih‐Che Chueh ◽  
Wei‐Hsin Chen ◽  
Kai‐Jen Chen
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Heat Transfer Performance ◽  
Waste Heat ◽  
Performance Comparison ◽  
Transfer Performance ◽  
Printed Circuit ◽  
Flow Channels

Performance Comparison of Rectangular and Air-Foil Shapes Offset Strip Flow Paths Micro Heat Exchangers

2007 ◽  
Author(s):  
Chien-Yuh Yang ◽  
Chun-Ta Yeh ◽  
Ting-Yu Lin
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Performance Comparison ◽  
The Other ◽  
Transfer Performance ◽  
Test Results ◽  
Flow Paths

Six micro heat exchangers with rectangle, airfoil and shuttle type strips was designed and fabricated in the present work. Two major parameters were considered for heat transfer performance comparison. One is the effect of strip type and the other is the strip arrangement. From the test results, we may notice that for both rectangle and airfoil strips heat exchangers, those with shorter strips performed lower thermal resistance than those with longer strips. Furthermore, the heat exchangers with more strips have better heat transfer performance. However, the space between strips is limited by the fabrication techniques.

Design Considerations and Heat Transfer Enhancement of CFB Heat Exchangers for Flue Gas Heat Recovery

2005 ◽  
Author(s):  
Yong-Du Jun ◽  
Kum-Bae Lee ◽  
Seok-Bo Ko ◽  
Sheikh Zahidul Islam
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Flue Gas ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Heat Transfer Performance ◽  
Fluid Composition ◽  
Generation Model ◽  
Transfer Performance

Now-a-day’s energy recovery process in the industry is a common practice for improving the production process while major concern goes to environment. The performance of the heat exchangers, used for the purpose of recovering energy, decreases continuously with time due to fouling depending on surface temperature, surface condition, construction material, fluid velocity, flow geometry and fluid composition. To overcome the fouling of fly ash on the heat transfer surface and erosion and periodical cleaning which are the major drawbacks in conventional heat exchangers for flue gas heat recovery, a no-distributor-circulating-fluidized-bed (NDCFB) heat exchanger with automatic particle controlling is devised. One of the main advantages of this model is the reduced pressure drop through the entire heat exchanger system, while increasing heat transfer performance. The research started with a single riser system with multiple down comers and multi-riser system is also studied. The heat transfer performance and pressure drop have been evaluated through experiments for these gas-to-water lab scale heat exchanger systems. However, due to the operational complexity, these two models are not readily applicable to real applications. As a derivation of the previous studies regarding the no-distributor CFB heat exchangers, third generation model of the heat exchanger is now under investigation.

Study of Performance Impact by Thermo-Hydraulic Developing Entrance in Spiral Microchannel With CFD Analysis

2016 ◽  
Author(s):  
Bing Li ◽  
Samuel D. Marshall ◽  
Rerngchai Arayanarakool ◽  
Lakshmi Balasubramaniam ◽  
Poh Seng Lee ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Waste Heat ◽  
Industrial Process ◽  
Microfluidic Channels ◽  
Transfer Performance ◽  
Developing Region ◽  
Region Length

Microchannel heat exchangers have become widely employed in modern systems, found within aerospace applications, waste heat recovery, water treatment processes, air conditioning, biomedical treatments and various industrial process applications. The microchannels increase the ratio of heat transfer surface to volume, thus improving the heat transfer performance significantly whilst reducing the overall weight and size. Moreover, by utilizing secondary flow from Dean Vortices induced by curved microfluidic channels, the fluid flow and heat transfer performance can be enhanced even further beyond conventional straight channels. However, since pressure drops found in microchannels are often quite high, channel lengths must be kept relatively short to balance the friction loss and energy consumption. Due to this, the developing region length at the microchannel entrance area has a greater impact than for macroscale channels, in terms of hydrodynamic and thermal performance over the remaining full developed region. The thermo-hydraulic design for heat transfer microchannel surfaces is strongly dependent on several dimensionless performance indicators, namely Nusselt number ‘Nu’ for heat transfer, and Poiseuille number ‘Po’, which is the product of Fanning friction factor ‘f’ and Reynolds number ‘Re’. These parameters are used to characterize and optimize the performance of microchannel surfaces and heat exchangers in general, also can be used to determine both the thermal and hydraulic developing region lengths at the channel entrance area. Whilst many such studies exist for theoretical analysis and experimental verifications, currently there is little literature on the developing region lengths and impacts researched through the method of Computational Fluid Dynamics (CFD). As such, this paper identifies and explores via quantitative analysis the hydraulic and thermal performance changes created by the relevant developing region lengths at the entrance area of spiral microchannels, as well as determinations and comparisons of these effects over straight channels. The numerical results, generated via COMSOL Multiphysics and contrasted with previous literature on the subject, also compared with the effect of the developing region on the effectiveness and efficiency of both spiral and straight microchannels, finding an improved heat transfer performance but an increased impact of hydraulic friction as well for spiral channels against straight counterpart. Furthermore, significant differences between thermal developing region length and hydraulic developing region length can be observed throughout, which illustrates high challenge and the need for compromise in microchannel design. In this way, implications for the configuration and design of industrial microchannels and micro heat exchangers are self-evident. All the key factors given in this paper are dimensionless, and thus the generated results can be utilized for a variety of flow conditions. Hence, this work should permit an increased understanding for and boost the curved microchannel and micro heat exchanger designs subsequently, through reducing the required numbers of tests and experiments and expediting the development for similar applications followed.

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